The present invention relates generally to die fingers for use in a crimping apparatus. More particularly, the invention relates to a crimping die for use in a crimping apparatus comprising a plurality of circumferentially spaced adjacent die fingers, each of said die fingers having an inner forming surface and an oppositely facing camming surface for engaging a cam of the crimping apparatus. Specifically, the invention relates to a crimping die wherein said die fingers having inner forming surfaces including a slot formed therein oriented along the longitudinal axis, wherein the slot has a length substantially equal to the length of the inner forming surface.
Crimping machines for crimping fittings onto the end of hoses, such as stem/ferrule single or two-piece couplings for hydraulic hose, are well known. It is well known in the production of hose assemblies to permanently secure a metal hose coupling onto the end of a hose by crimping a ferrule around the hose to cause the hose to be tightly held between the ferrule of the coupling and a fitting positioned inside the hose. In the crimping process, the crimping die engages the entire ferrule of the coupling. The crimping die reduces the ferrule in diameter to secure the coupling to the hose end.
The crimping die is typically constructed from a plurality of circumferentially spaced die fingers. The crimping die typically has an inner surface that is substantially cylindrical and an oppositely facing cam surface sized for engaging a cam of the crimping apparatus. The die fingers are spaced apart from each other in an expanded mode so as to permit the hose coupling which is to be crimped to be placed in the center of the crimping die. The die fingers are then driven, typically by a hydraulic ram of the crimping machine, in the direction of the ferrule to be crimped. This causes simultaneous radial inward movement of the die fingers and a contraction of the crimping die. With the ferrule of the hose coupling positioned within the center of the crimping die, radial inward deformation is effected to secure the coupling onto the hose end.
Crimping dies are typically constructed with eight die fingers. The radial deformation caused by the eight finger crimping die results in a matching eight segment deformation in the collar/ferrule of the coupling. After crimping, the ferrule of the coupling has eight grooves and eight ribs. The eight ribs are created from the material flowing in between the eight die fingers during crimping. After crimping with an eight finger die, the inside diameter (ID) of the crimped ferrule resembles an octagon. The apexes of the octagonal shape form potential leak paths in the hose coupling.
A prior art hose coupling, U.S. Pat. No. 5,267,758 to Shah, et al., solves the problem of potential leak paths in the apexes of the octagonal ID of the ferrule. U.S. Pat. No. 5,267,758 discloses a ferrule containing a C-shaped insert. When a ferrule with a C-shaped insert is crimped onto a hose, the C-insert bends to a substantially round shape in contrast to a polygonal shape. The C-insert does solve the potential leak path problem but is not used on all ferrule product lines, due to the added expense of the C-insert. Hose ferrules are still used that do not utilize the C-insert and thus still have the problem of potential leak paths in the apexes of the octagonal ID of the ferrule.
Although the C-insert of U.S. Pat. No. 5,267,758 solves the problem of potential leak paths as described above, other problems do exist after crimping the ferrule containing the C-shaped insert. These other problems also exist with conventional ferrules that do not contain the C-shaped insert. When crimping a ferrule with a crimping die constructed from eight die fingers, eight ribs are created from the excess material flowing in between the eight die fingers during crimping. Due to the material flow there is a tendency for these ribs to be very uneven and have sharp, unsafe edges.
In many applications, the same size ferrule is crimped onto a hose with the same size inside diameter (ID) but having a large range of outside diameters (ODs). For example, the same size ferrule may be crimped onto 3/8 in. ID hose with hose ODs ranging from 0.62 to 0.80 in. The recommended crimp OD of a ferrule crimped onto a 3/8 in. ID, 0.74 in. OD hose is 0.89 in., whereas the recommended crimp OD of the same size ferrule crimped onto a 3/8 in. ID, 0.625 in. OD hose is 0.81 in. The rib problems mentioned above with uneven or sharp edges are more prominent in the latter of the two examples. This is because when crimping the standard ferrule to a smaller crimp OD, more metal must flow between the die fingers than when crimping to a larger crimp OD. When crimping the standard ferrule to a smaller crimp OD, the eight finger crimp may tend to be uneven or bulge due to insufficient pressure about the ferrule during the crimping process. As a result, the extra metal flow between the die fingers may form uneven and sharp ribs on the crimped ferrule.
The need remains, particularly in the area of crimping machines for radially crimping the ferrule of a hose coupling onto the end of a hose, for a method of crimping that solves the problems of sharp, uneven ribs in a crimped ferrule and of potential leak paths in a ferrule not having a C-insert.